Plastic fasteners are commonly utilized in the retail industry in a variety of different applications to couple together two or more separate items. For instance, plastic fasteners are often used to couple together (i) a pair of complementary articles of clothing, such as socks, gloves and the like, (ii) a merchandise tag, or ticket, to one or more articles of clothing (e.g., a merchandise ticket folded over the waistline of a pair of jeans), and (iii) a handheld item (e.g., a tool or toy) to its corresponding packaging (e.g., a screwdriver disposed against the front surface of a flat, cardboard display card).
In U.S. Pat. No. 4,039,078 to A. R. Bone, the disclosure of which is incorporated herein by reference, there are disclosed several different types of plastic fasteners. Each plastic fastener described in the patent is manufactured in a generally H-shaped configuration, with two shortened parallel cross-bars, or T-bars, being interconnected at their appropriate midpoints by a single, thin, flexible filament which extends orthogonally therebetween.
Plastic fasteners of the type described above are commonly fabricated as part of a continuously connected supply of fastener stock, which is also commonly referred to in the art simply as ladder stock due to its ladder-like appearance. Referring now to FIG. 1, there is shown a length of ladder stock that is presently manufactured and sold by Avery Dennison Corporation of Pasadena, Calif. under the PLASTIC STAPLE® and ELASTIC STAPLE™ lines of plastic fasteners. As can be seen, a length of ladder stock is shown that is preferably produced from one or more flexible plastic materials, such as nylon, polypropylene and the like, the ladder stock being identified generally by reference numeral 11. Ladder stock 11 comprises a pair of elongated and continuous side members, or rails, 13 and 15 which are interconnected by a plurality of equidistantly spaced cross-links 17.
An individual plastic fastener 18 is obtained from ladder stock 11 by severing side members 13 and 15 at the approximate midpoint between successive cross-links 17. As can be seen, each fastener 18 comprises a pair of cross-bars 19 and 21 which are interconnected by a thin, flexible filament 23, with cross-bars 19 and 21 comprising sections of side members 13 and 15, respectively, and filament 23 comprising a cross-link 17.
Automated plastic fastener dispensing devices, or machines, are well known in the art and are commonly used to dispense individual plastic fasteners from a reel of ladder-type fastener stock. For example, in U.S. Pat. No. 8,413,866 to W. J. Cooper et al., the disclosure of which is incorporated herein by reference, there is disclosed one well known type of plastic fastener dispensing device that is presently manufactured and sold by Avery Dennison Corporation of Pasadena, Calif. as the ST9500® fastener system, the fastener dispensing device being shown in FIG. 2 and identified therein by reference numeral 30. As can be seen, fastener dispensing device 30 is designed to dispense individual plastic fasteners from a reel of continuously-connected ladder stock 11.
Fastener dispensing device, or machine, 30 comprises a substantially enclosed, protective housing 39 that serves to protect the majority of the electrical and mechanical components for device 30. An arcuate recess 41 is formed in the top surface of housing 39. A cylindrical reel holder 43, which is mounted onto housing 39, extends laterally through recess 41 and is dimensioned to pass axially through a longitudinal bore formed in a reel, or spool, 45 around which ladder stock 11 is wound. Accordingly, holder 43 serves to support reel 45 within recess 41 and enable reel 45 to rotate freely during normal operation, thereby rendering device 10 capable of continuously dispensing plastic fasteners in an automated fashion.
Fastener dispensing device 30 additionally includes a motor-driven head assembly 53 that is disposed within the front end of protective housing 39 and is responsible for, inter alia, dispensing an individual fastener 18 from ladder stock 11. Specifically, head assembly 53 includes a vertically extending mount 55 that is fixedly retained in place, mount 55 being generally U-shaped in lateral cross-section. A motor-driven, vertically displaceable head 57 is slidably coupled to mount 55 for purposes to become apparent below.
Head assembly 53 comprises a pair of hollow, slotted needles 59-1 and 59-2 that is fixedly coupled to vertically displaceable head 57 and is therefore adapted to selectively penetrate through the one or more items to be fastened, a feed mechanism 61 for advancing side members 13 and 15 of ladder stock 11 into axial alignment behind the longitudinal bores defined by needles 59-1 and 59-2, respectively, a severing mechanism 63 for cutting side members 13 and 15 of ladder stock 11 at the approximate midpoint between successive cross-links 17 to separate an individual plastic fastener 18 from the remainder of ladder stock 11, and an ejection mechanism 65 for ejecting cross-bars 19 and 21 of the severed fastener 18 through the bores of the pair of hollowed needles 59 and, in turn, through the one or more items previously penetrated by needles 59.
Referring now to FIGS. 3(a)-(c), there are shown front perspective, top plan and front plan views, respectively, of fastener dispensing needle 59. As can be seen, needle 59 comprises an elongated, generally cylindrical, slotted stem 71 that is hollowed out along its length so as to define a longitudinal bore 73. Stem 71 includes a trailing end, or base, 75, which is appropriately dimensioned for mounting within head 57, and a spoon-shaped leading end 77 with a sharpened tip 79 designed to facilitate penetration through the desired articles. As can be appreciated, bore 73 is sized and shaped to axially receive a cross-bar (e.g., either cross-bar 19 or cross-bar 21) of fastener 31, thereby enabling the cross-bar to be inserted into bore 73 from trailing end 75, travel axially therethrough along its length, and ultimately exit from bore 73 through open leading end 77.
As referenced above, each fastener dispensing needle 59 is vertically driven by head 57 and designed to selectively penetrate through the one or more items to be fastened during the dispensing process. Referring now to FIGS. 4(a)-(c), there is shown a series of views depicting a conventional method in which each fastener dispensing needle 59 penetrates through material 81 during normal operation of a fastener dispensing machine (e.g., prior art machine 30). For simplicity purposes, material 81 is represented herein as a single layer of fabric which includes a first, or top, surface 83 and a second, or bottom, surface 85.
As seen in FIG. 4(a), needle 59 is oriented vertically downward with sharpened tip 79 positioned close in relation to first surface 83. Through motorized displacement of head 57, each needle 59 is driven vertically downward so as to penetrate material 81, as represented by arrow P in FIG. 4(b). As can be seen, the forward stroke SF of needle 59 extends from first surface 83 (or in close proximity thereto) to slightly beyond opposing surface 85 (i.e., with enough clearance that the fastener cross-bar can exit bore 73).
Upon ejection of the fastener cross-bar through needle 59 and, as such, through material 81, needle 59 is withdrawn from material 81, as represented by arrow W in FIG. 4(c). As can be seen, the rearward stroke SR of needle 59 extends from slightly beyond surface 85 back to surface 83 (or in close proximity thereto). With needle 59 withdrawn, a hole 87 typically remains in material 81 due to the needle penetration process.
Accordingly, in summation, the penetration cycle for needle 59 consists of a single forward stroke SF that extends through the entirety of material 81 and a single rearward stroke SR that completely withdraws needle 59 from material 81. As can be appreciated, fastener dispensing devices that utilize a needle penetration cycle as set forth above have been found to experience a notable shortcoming.
Specifically, it has been found that needle 59 is prone to lateral deflection using the above-described penetration cycle, particularly when material 81 is of a considerable thickness and/or density. Lateral deflection of needle 59 away from its ideal linear penetration path can result in either (i) permanent bending or breakage of needle 59 and/or (ii) significant widening of hole 87, which often results in notable damage to material 81.